This invention relates generally to apparatus for charging an automobile air conditioning system with refrigerant. More particularly, this invention relates to an improved do-it-yourself charging kit for automobile air conditioners.
Automobile air conditioning systems require periodic servicing to insure that refrigerant in the system is maintained at the proper level for safe and efficient operation. For this reason, valved charging nipples are commonly located at or near both the low pressure suction port and the high pressure discharge port of the system compressor to facilitate the periodic addition of refrigerant through either port into the system.
Do-it-yourself charging kits have been developed to enable an owner to charge his automobile air conditioner with refrigerant himself. Such do-it-yourself kits are only practical for injecting refrigerant into the low pressure suction port of the compressor, since pressures at the high pressure port are too great to be overcome except with special equipment. A do-it-yourself kit should be manufactured from inexpensive materials so that it can be discarded after the refrigerant supply has been expended.
A common do-it-yourself kit comprises a pressurized can containing a supply of refrigerant, a puncture fitting for tapping the refrigerant supply and containing a check valve and a heavy duty hose for delivering refrigerant from the puncture fitting to the low pressure suction port of the compressor. In use, the heavy duty hose is first coupled between the valved puncture fitting and the suction port of the compressor. The puncture fitting is mounted over the top of the pressurized can of refrigerant. The puncture fitting is then operated to pierce a hole in the top of the can to tap the supply of refrigerant, and to seal itself by a gasket to the can to minimize refrigerant leaks. The check valve of the puncture fitting prevents backflow from the hose to the can to protect the can against high pressure backflow from the compressor in the event the system pressure should be greater than the can pressure. This is especially important in the event the hose is mistakenly coupled to the high pressure discharge port of the compressor, since the high pressure at such port could cause the can to explode.
This prior charging kit is relatively expensive, both because the required puncture fitting and check valve is relatively complicated and expensive, and because the arrangement exposes the hose to possible high pressure and therefore requires an expensive high burst-strength hose to meet government safety standards. Such government standards require that the delivery hose be capable of withstanding at least 3.5 times the maximum possible working pressure on the hose. In the event the hose is inadvertently coupled to the high pressure port of the compressor, the hose is subjected to pressures on the high side of the compressor which can reach up to about 350 psi. Consequently, a heavy-duty refrigerant hose having a bursting strength of about 1,750 psi is commonly used. With the prior system, once the pressurized can of refrigerant has been opened by the puncture fitting, any unused refrigerant in the can is wasted because the can cannot be effectively resealed.
The present invention overcomes all the problems and difficulties mentioned above by providing a do-it-yourself charging kit which eliminates the complicated and expensive puncture fitting, utilizes a resealable can of pressurized refrigerant, and isolates both the delivery hose and the pressurized can of refrigerant against backflow from the compressor so that the delivery hose and its fittings can be made of inexpensive materials while providing equal or better safety.